22ZO

Single full-length subunit of the Vpb4Aa2 pore complex

Summary for 22ZO

• Entry DOI: 10.2210/pdb22zo/pdb
• EMDB information: 71647
• Descriptor: Vip4, CALCIUM ION (2 entities in total)
• Functional Keywords: vpb4, vip4, bacterial toxin, pore-forming toxin, translocase, insecticidal, toxin
• Biological source: Bacillus thuringiensis
• Total number of polymer chains: 1
• Total formula weight: 84054.70

Authors

Wirawan, R.,Lupton, C.J.,Venugopal, H.,Berry, C.,Dunstone, M.A.,Spicer, B.A. (deposition date: 2026-01-29, release date: 2026-06-24, Last modification date: 2026-07-15)

Primary citation

Wirawan, R.,Jamieson, W.D.,Baird, H.M.,Berry, C.,Lupton, C.J.,Venugopal, H.,Valentin-Alvarado, L.E.,Best, H.L.,Jones, D.D.,Williamson, L.J.,Auhim, H.S.,Castell, O.K.,Dunstone, M.A.,Spicer, B.A.
Structural basis for independent pore function of Vpb4 from Bacillus thuringiensis.
Nat Commun, 2026

PubMed Abstract: The Bacterial_Exotoxin_B family constitutes translocating pore-forming proteins that function as the binding (B) component in the binary AB Toxin mechanism. While the two-component system of the family is consistent among well-characterised members, the single-component Vpb4 subclass from entomopathogenic Bacillus thuringiensis challenges this dogma. Here, through single-particle cryo-electron microscopy, we elucidate the inserted pore structure of a Vpb4 member, Vpb4Aa2, at 2.2 Å resolution. The structure reveals distinguishing features from other family members: missing molecular bottleneck and neutrally charged β-barrel. Accordingly, preliminary electrophysiology studies show greater ion flux by Vpb4Aa2 compared to archetypal family member, PA. Through our findings, structure-guided database search allows identification of putative Vpb4-like proteins, which suggest a broader class of single-component proteins within the larger family. This provides mechanistic understanding of the differences between independent pores and translocating pores, with implications in the agricultural industry for screening and identification of future pest control candidates.

PubMed: 42386714
DOI: 10.1038/s41467-026-74567-y

Experimental method

ELECTRON MICROSCOPY (2.2 Å)